1. Field of the Invention
The invention relates to biotechnology and more particularly to a method of rapidly inducing large-scale and high-purity mesenchymal stem cells to transdetermine into hematopoietic stem cells.
2. Description of Related Art
White adipose tissue (WAT), the main source of adipose-derived stem cell (AD-MSCs), is widely distributed in the body and abundant. Cell cloning experiment has proved that bone marrow derived mesenchymal stem cells (Bone-marrow mesenchymal stem cell, BMSCs) only is 0.2×10−5-0.1×10−5 of adult bone marrow, and the cloning efficiency of stem cell obtained from adipose tissue is 100-500 times of that of BMSCs. The proportion and proliferation ability of BMSCs in bone-marrow descends with the increasing of age and incidence rate of osteoporosis, but the quantity of ADSCs in adipose tissue does not decrease with the increasing of age of the donors. The ability of amplification in vitro and renewability of ADSC is strong, and cell fusion is more than 90% after 5-7 days of primary culture, and Logarithmic growth phase occurs three times in one month, and can be passaged stably more than 20 generations; It is not special selectivity for serum when cultured in vitro, and can grow well without additives, and growth and phenotype of ADSCs is not changed after freezing of liquid nitrogen and long-term passage generations.
ADSCs has multipotent differentiation capacity, and ADSCs can directionally differentiates into a variety of tissue cells, such as osteoblast, chondrocytes, adipocytes, endothelial cells, skeletal muscle cells, cardiac cells, pancreatic endocrine-like cells, liver cells and optic nerve cells etc. under different induced culture conditions. But it is not clear whether they can be transformed into hematopoietic stem cell (HSCs) till now.
Hematopoietic stem cell is the most effective method of treating hemopathy, especially for leukemia. Leukemia has the trend of increasing significantly in China recently as same as other tumor diseases, and presents the character of younger-age trend. Leukimia accounts for 5% of malignant cancer, and incidence is in the majority in children and young people. The most effective method of treating leukemia is hematopoietic stem cell treatment. Families of patients and related sectors of society use all available resources to find a suitable matching hematopoietic stem cells, but the possibility of matching is extremely small. Therefore it is pushed the establishment of a national stem cell bank, but the expense of each bank is about 2 hundred million yuan, and its high economic cost can be imagined. But technically it is not completely rule out the possibility of immune rejection and tumorigenesis. Furthermore, the high-quality medical treatment can not be assured due to limited quantity of stem cells and lacking of non-differentiated amplification technique. For all those above-mentioned reasons, it exists urgent need for people to discover new sources of hematopoietic stem cells and to develop new techniques and methods of non-differentiated amplification of hematopoietic stem cells.
Recent research has discovered that the expression of small RNA in different types of hematopoietic cells is significantly different, and the difference plays very important regulation effect in the process of cell development. For instance, iR-181 is related with B-lymphocyte development, miR-142 and miR-223 are related with development of T-lymphocytes, miR-221 and miR-222 are related with human erythrocytopoiesis, miR-223 is related with granulocyte cell differentiation of mice, and miR-10, miR-126 and miR-17 are related with decreasing of megakaryocyte. Beyond that, people also discovered that some miRNA, such as miR-130a and miR-10a, induce cell differentiation through affecting transcription factor genes of HOXA1 gene and MAFB gene.